1. Field of the Invention
Example embodiments of the invention relate to organic light emitting display (OLED) devices and methods of manufacturing organic light emitting display devices. More particularly, example embodiments of the invention relate to organic light emitting display devices including uniform organic light emitting structures formed by pixel defining layers having fine uneven structures and methods of manufacturing the organic light emitting display devices.
2. Description of the Related Art
Generally, an organic light emitting display device displaying color images may include a lower electrode disposed over a substrate, a pixel defining layer formed on the lower electrode, organic layers formed on the pixel defining layer and the lower electrode, and an upper electrode positioned on the organic layers and the pixel defining layer. The pixel defining layer may be located on an insulation layer covering an underlying structure and the lower electrode, and the pixel defining layer may insulate the organic layers of adjacent pixels while defining a display region of the organic light emitting display device.
In the display region defined by the pixel defining layer, the organic layers may include a red organic light emitting layer (EL), a green organic light emitting layer and a blue organic light emitting layer in accordance with color pixels, and the organic layers may additionally include a hole injection layer (HIL), an electron injection layer (EIL), a hole transfer layer (HTL), an electron transfer layer (ETL), etc. Here, the organic light emitting layer may be formed using an organic polymer or an organic material having relatively low molecular weight.
Typically, the organic layers may be formed by a laser induced thermal imaging (LITI) process in which organic transfer layers of a donor substrate including a light to heat conversion layer and the organic transfer layers may be transferred onto the lower electrode of the organic light emitting display device. In the laser induced thermal imaging process, the donor substrate may be laminated on the pixel defining layer and laser energy may be applied to the donor substrate so that the organic transfer layers may be expanded and detached from the donor substrate. Thus, the organic layers may be formed on the portion of the lower electrode left exposed within and surrounded by the pixel defining layer by transfer of organic layers that detach from the donor substrate. However, in the conventional method of manufacturing the organic light emitting display device, gases may easily remain trapped at both end portions of the display region (i.e., on both of the end portions of the lower electrode). The remaining trapped gas on the lower electrode surface may prevent the organic layers from being properly formed on the lower electrode and specifically on the end portions of the display region. This failure of the organic layers to adhere may be referred to as “edge open failure”. When edge open failure occurs in the display region, the lifetime of the organic light emitting display device may be reduced, and the uniformity of images displayed by the organic light emitting display device may be deteriorated.